Problem: Solve for $p$ : $17 = p - 3$
Answer: Add $3$ to both sides: $ \begin{eqnarray} \\ \hphantom{17 {+ 3}} &\hphantom{=}& \hphantom{p} \\ 17 &=& p - 3 \\ \\ {+3} && {+3} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 17 {+ 3} &=& p \\ \end{eqnarray} $ Simplify. $ p = 20$